Experimental analysis of the tribological behavior of boron nitride in aluminum matrix composites with reciprocating motion

New aluminum based metal matrix composites (AMCs) were prepared by the powder metallurgy method. The base material of the AMCs was 6061 aluminum alloy powder. The solid lubricant filler was boron nitride (BN) powder, blended into the matrix material at five different wt.%'s. Cold pressing, degassing, and sintering processes were then applied to obtain the specimens. The material of the counter-face specimen was AC8A cast aluminum alloy. Tribological tests were performed under dry contacts, and reciprocating motion was done using a vanes-on-disk adapter. The experimental results reveal that the porosity and the hardness of the upper specimen are two dominant factors affecting the wear loss of either the lower or the upper specimen. Although increasing the BN content in the composites elevates the material porosity, this can impede the rise of the wear rate. The wear rate of the upper specimen, irrespective of the BN content, is the main factor that controls the average rate of wear displacement. The average friction coefficient increases with an increasing BN content filled in the upper specimen. The lowest wear rate of the upper specimen and nearly the lowest wear rate of the lower specimen occurred at the upper specimen with 4 wt.% BN content even though its friction coefficient is not the smallest. By increasing the BN content at the upper specimen, the quantity of the upper specimen transferred to the lower specimen can be effectively reduced.